In a silver halide color photographic material, it is required, as well as high sensitivity, that fluctuations in photographic characteristics are less during storage after manufacture of a photographic material and also after photographing until development processing.
Of the fluctuations in photographic characteristics after photographing until development processing, with respect to the prevention of latensification, a method by the combined use of a hardening agent having an active vinyl group with a triazine based compound is disclosed, for example, in JP-A-59-162546 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
However, the above method is not sufficient in the preventing effect and a further improvement has been desired.
On the other hand, in a full color photographic material, a multilayer structure comprising a plurality of emulsions having different spectral sensitivities is used to achieve the object of a full color photograph. However, although the emulsions for such a usage have been considerably improved, fog, intensification and fading of a latent image are liable to occur, therefore, they are not necessarily sufficient. 2-Hydroxyamino-1,3,5-triazines, for example, are useful for the improvement of such storage stabilities. However, the above storage stability improver used in each layer varies according to the emulsion used in each layer. Accordingly, a method to improve the storage stability of the latent image of the emulsion of rather a specific layer has been strongly desired in recent years.
Many of known 2-hydroxylamine-1,3,5-triazines are diffusible, therefore, these compounds have a drawback such that their function is exerted also to emulsions of layers other than the objective layer. On the other hand, hydroxamic acids having specific structures are disclosed in JP-A-59-198453 and JP-A-3-293666, but their use purposes are different from the object of the present invention and, further, their effect of the improvement of the storage stability of a latent image and the function to the emulsion of solely a specific layer are not sufficient. Accordingly, the development of a method to largely improve the storage stability of the latent image of only the objective layer has been strongly desired.
The present invention is to provide a method for improving the above-described storage stability of the emulsion and the stability of the latent image of a specific layer.
The present inventors have eagerly studied the method of improving the storage stability of an emulsion produced and the storage stability of a latent image to solve the above problems. As a result of various investigations particularly about the carbon atom number and the kind of substituents of storage stability improvers, a completely novel N-alkylhydroxamic acid based compound of the present invention which has a specific substituent and a carbon atom number has been discovered.
Further, it has been found that the compound of the present invention can achieve the objects of the present invention, when added to a silver halide photographic material, without changing the hue of the dye formed, affecting the dye-forming speed of a coupler, accelerating the decomposition of a coupler and the dye formed, deteriorating the film strength, or fogging an emulsion.
Still further, it has been found that the hydroxamic acid based compound according to the present invention shows a sufficient improving effect of the storage stability of a latent image and an emulsion with a reduced amount of addition.
Moreover, the compound according to the present invention is a completely novel compound which has not been known in the past. The photographic usefulness of this compound has become clear solely by the investigations of the present inventors.